<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框样式演示</title>
    <style>
        #id1{
            /*设置所有边框*/
            border: 5px black solid;
            width: 200px;
            height: 200px;
        }
        #id2{
            /*设置上边框 solid-实线*/
            border-top: 5px red solid;
            /*设置下边框 double-双实线*/
            border-bottom: 5px gold double;
            /*设置左边框 dotted-圆点*/
            border-left: deepskyblue 5px dotted;
            /*设置右边框 dashed-虚线*/
            border-right: green 5px dashed;

            width: 200px;
            height: 200px;
        }
        #id3{
            border: 5px black solid;
            width: 200px;
            height: 200px;
            /*设置边框弧度*/
            border-radius: 50px;
        }
    </style>
</head>
<body>
    <div id="id1"></div> <br/>
    <div id="id2"></div> <br/>
    <div id="id3"></div> <br/>
</body>
</html>